Cost sharing in defense acquisition, with contractors sharing part of the burden of research development, test, and evaluation (RDT&E) costs, has been suggested as a way of reducing the liability of governments to program cost overruns. While capping the costs of RDT&E and production is an excellent objective, incentivizing contractors may benefit from business models that span the entire lifecycle of a program. The potential to share the risk of cost overruns outside of RDT&E and production, and into the operations and support (O&S) area provides a powerful incentive to get contractors to buy in to cost sharing, and to control total program lifecycle costs.